The present invention relates generally to an electric drive apparatus and an electric power steering apparatus, and particularly to an electric drive apparatus and an electric power steering apparatus in which an electronic control unit is provided.
In recent years, an electric drive apparatus of mechatronical integration type is employed in various industrial fields. This electric drive apparatus includes both of an electric motor and an electronic control unit in a package, wherein the electric motor is configured to drive a controlled object of a mechanical system, and wherein the electronic control unit (ECU) includes semiconductor elements and others for controlling rotational speed and torque of the electric motor. Examples of electric drive apparatus of this type include an electric power steering apparatus, an electric brake apparatus, and an electric hydraulic pressure control apparatus for an automotive vehicle. The electric power steering apparatus of this type includes an electric motor, and an electronic control unit or section for controlling the electric motor, wherein the electronic control unit is configured to receive a sensing signal indicative of rotational speed and torque of a steering shaft rotated by driver's operation of a steering wheel, and control the electric motor based on the sensing signal, to produce a steering assist torque applied to the steering shaft.
Japanese Patent Application Publication No. 2015-134598 (corresponding to US 2015/0180316 A1) discloses an electric power steering apparatus composed integrally of an electric motor section and an electronic control section. In the electric motor section, an electric motor is housed in a motor housing, wherein the motor housing has a cylindrical part made of an aluminum alloy or the like. In the electronic control section, a board provided with electrical components is housed in an electronic control section housing (or ECU housing), wherein the electronic control section housing is arranged at a side of the motor housing opposite to an output shaft of the electric motor in its axial direction. The board is provided with a power supply circuit part, a power conversion circuit part, and a control circuit, wherein the power conversion circuit part includes power switching elements such as MOSFETs (metal-oxide-semiconductor field-effect transistors) or IGBTs (insulated gate bipolar transistors) for driving and controlling the electric motor, and wherein the control circuit part is configured to control the power switching elements. Output terminals of the power switching elements and input terminals of the electric motor are connected electrically via a bus bar.
The electronic control section housed in the electronic control section housing is supplied with electric power from a power supply via a connector terminal assembly made of synthetic resin, and also supplied with a sensing signal indicating operating states and others from sensors and others. The connector terminal assembly serves as a cover covering an opening of the electronic control section housing while being connected to the electronic control section, and fixed to an outer surface of the electronic control section housing by fixing bolts.